Detachable blade bit



Nov. 11, 1958 J, HAWTHORNE 2,859,942

DETACHABLE BLADE BIT Original Fil ed Dec. 29, 1947 INVENTOR IV /2852*? I #Aums ews M QMZWMM v ATTORNEYS United States Patent DETACHABLE BLADE BIT Herbert J. Hawthorne, Houston, Tex., assignor of onefourth to Earl M. Weaver Continuation of Serial No. 332,060, January 19, 1953, which is a division of application Serial No. 794,239, December 29, 1947, now Patent No. 2,666,622, dated January 19, 1954. This application May 15, 1957, Serial No. 659,423

1 Claim. (Cl. 255-61) This invention pertains to drilling bits for drilling earth formations.

This application is a continuation of my copending application Serial No. 332,060, filed January 19, 1953 for Detachable Blade Bit and now abandoned. Serial No. 332,060 is a division of my earlier filed application Serial No. 794,239, filed December 29, 1947, now Patent 2,666,- 622. Accordingly, the present application is entitled to the aforesaid filing date of December 29, 1947.

Detachable blade bits of the type herein described are generally referred to in the well drilling art as drag bits since the cutting action against the formation by the bit is accomplished by rotating the bit so that the blades drag against the formation so as to cut into the formation as the bit rotates.

Heretofore, a great deal of difliculty has been encoun- 'tered in attempting to keep the blades of the bit firmly secured in position on the body. This is due to the fact that a weight is usually placed immediately above the drill bit so that the bit will be pushed downwardly against the formation as it is rotated. Techniques for overcoming these difficulties are described and claimedin the above-mentioned applications.

The invention described and claimed herein is of utility regardless of particular means for attaching blades to a bit body.

An object of the invention is to provide a drag bit having a plurality of blades of claw-like construction which are constructed so as to dig into the formation being drilled as the bit is rotated.

Other and further objects and advantages of the invention will become more readily apparent when the following description is considered in connection with the accompanying drawing wherein:

Fig. l is a partially exploded view of a form of a bit in which the invention is embodied;

Fig. 2 is an elevational view showing the bit of Figure 1 assembled;

Fig. 3 is a rear elevational view showing a modification of the blade construction;

Fig. 4 is a front elevational view of the blade in Fig. 3;

Fig. 5 is a bottom plan view looking up at the bottom of a bit constructed in accordance with the present invention and having a blade construction in accordance with that shown in Figs. 3 and 4.

In Fig. 1 a bit is shown generally at 2 and comprises a body 3 with the threaded shank 4 and a tapered body portion 5 thereon. A passage 3' extends through the body 3 for pumping of flushing fluid therethrough. Spaced from the end 7 of the body portion 5 is a groove 8 on the outer periphery of the body 3. A plurality of notches 10 are cut in the end 7 and extend up to the groove 8 of the body 3 to receive the formed portion 11 of the blades 12 to support the blades and the body, as will be more fully described. While there may be any number of notches in the body so as to accommodate a like number of blades, as a practical matter, it has been found shown "ice that the number of blades used will not exceed 3 or 4. If 3 blades are used, a body 3 is used which has three notches 10 which are 120 apart on the end 7 of the body 5; if 4 blades are used, a body 3 is used which has 4 notches which are apart on theend 7 of the body 3.. The blades will thereby be spaced about the body an equidistance apart.

The blades 12 comprise a curved portion 13 which. is arranged to fit the curved body portion 5 of the bit body 3. The formed portion 11 is integral with the curved portion 13 of the blades 12 and is formed by the surface 14 which is upstanding from the curved portion 13 and surface 15 which meets surface 14 substantially at right angles to form the edge 16 which fits in the corner. of the notch 10 on the body 3. The surface 14 of the blade fits against the surface 14' of the notch 10 and the surface 15 fits against the surface 15' of the notch. Upstanding between the curved portion 13 and the surface 14 of the blade is a projecting shoulder or ledge 17 which is of a size to fit into the groove 8. It therefore seems obvious that when the portion 11 of the blade 12 is placed in the notch 10 and the shoulder 17 inserted into the groove in Figs. 2 and 5, the blade will be firmly positioned on the bit body.

In order to retain the blades in position on the body, a collar 19 is provided which has an internal taper 20 of a size to fit over the outer periphery of the curved portion 13 of'the blades 12. In order to prevent slipping of the retainer collar 19, the drill collar 21 is provided with internal threads 22 arranged to engage the threaded shank 4. When the bit is assembled, the drill collar 21 will engage the end 23 of the retainer collar 19 to clamp the blades 12 in position on the body.

Since the blades are positioned in the notches 10 and the groove 8 and are held thereon by the retainer collar 19, it is impossible for the body to move relative to the blades 3. The blades cannot move back and forth on a radius since the body and blades for all practical purposes are retained as an integral unit by the collar 19; nor can they move angularly about the body because they are positioned on the body in the notch and no vertical movement can occur between the blades and the body since the taper on the inner surface of the collar and the taper on the body is such that the blades are held permanently in position therebetween. The taper on the collar 19 is such that when the bit is assembled a double vising effect is produced between the body 3 and the collar 19 to retain the blades firmly in position during operation of the bit.

Features of the blade clamping arrangement are claimed in the above-mentioned patent. That patent may be referred to for a fuller description of the blade clamping arrangement.

Particular attention is directed to the construction of the blades shown in Figs. 3, 4 and 5 wherein the downwardly extending plate 11' forms a cutting portion which terminates in the stepped cutting edges 30. These also may be termed cutting fingers. The front, or cutting surface of the downwardly extending plate, is substantially fiat or planar as shown in Fig. 3 whereas the rear portion is of a claw like construction as shown in Fig. 4. Extending upwardly from each stepped point 30' of the cutting edge is a rigid surface 32 which is tapered on each side of 33 and 34 thereof. This construction affords rigidity to the blade by forming a stifiening rib or ridge and permits the blade to be used over a longer period of time before retipping or resharpening of the blade is necessary. It is also apparent that more cutting material exists in the fingers than in the webs therebetween. Therefore, the webs will wear away more quickly than the fingers, thus preserving the profiles ofi V 3 the cutting portions of the blades all during the useful life thereof.

It is also to be noted that the steps in the blades are displaced relative to each other. As shown in Fig. 5, the, steppedpoint- 35 is nearer the center of thebit body'tharr; is the steppedpoint- 36,'whereas; the stepped point 37 is'- intermediate the two; The blades, of course, extendra-- dially from the bit body the same amount, the one difference being that-eachcutting edge point--isdisplacedalongthe cutting edgerelative to -the'same cutting edgepoint in the next adjacent blade. The cutting edge points will therefore not followin the path cut by the previous cutting'edge point but' rather; each cuts -its ownpath; thereby increasing the efliciency of--the-bit as-it rotates-.-

Since it is desiredto-maintain-the pr0file of*the -bore bottom, and since theouter-fingers will travel a greater distance than more inwardly placed fingers; a greater number oftracking-as-distinguished from non-trackingfingers are provided outwardly of-the rotational axis--of the bit. Asisclearly shown in Figure- 5,; where three cutting blades are illustrated, there is a tracking-finger on each blade for the outermost groove. Similarly, there is a tracking finger on each-blade for the-neXt'innermost' groove. However, further'toward the center of the-bit, the fingers of the respective blades 'are-non-tracking. If all of the fingers are non-tracking, the outer onestravellingat greater distances'would Wear down more-rapidly,

A' drag .typerotary drilling bit comprisinga .body', .a...

plurality of blades on the body, each blade having a cutting portion having a planar front or cuttingsurface, each.

cutting portion having cutting fingers extending downwardly therefrom, the cutting surface of the fingers being substantially in a continuation ofsaid planar surface, the lower extremities of the respective fingers on ,each blade being stepped upwardly androutwardly of the bit center, the rear of each blade beingcharacterized by ridges extending upwardly from the fingers, the cutting portion of a 'each blade including web portions extending between the thus changing the profile of the bore bottomt It-will be understood, of course, that my invention is not-broadly limited to this particular arrangement of tracking and non-tracking fingers.

It seems obvious that blades of difierent size may be fingers thereof, the web portionbetween each pair-of fingers beginning substantially at theradially outer side thereof at the lowermost extremity of the radially outermost finger of the pair for providing support to the cut-- ting fingers, said webs having lesser cutting ability than the fingers.

References-Cited in the file of-this patent UNITED STATES PATENTS 1,361,734 Katulka Dec. 7; 1920 1,978;084l Howard Oct. 23, 1934 2,504,978 Henning Apr..25, 19504 

